Well, the Jedi focus on the Light side of the Force, the side of "no emotion, emotion is bad, emotion leads to the Dark side." Sith, on the other hand, focus on the dark side of the Force, reveling in our emotions and conquering all weaker than ourselves. This "magic" you speak of is the Force. The Force lets us "Force Wielders", a alignment neutral terms for someone who wields the Force and sometimes carries a lightsaber, do some crazy awesome things, like shooting lightning from our hands and suffocating people with our minds. The whole "shooting lightning" thing is kinda looked down upon by the Jedi, who prefer peace to war, boring buncha twats. Torin says before blasting lightning from his hand in a direction in which nobody Torin knows will be hurt. See? Fun stuff. Theirs also the whole "mind trick", which lets us mess with your mind. For example, do you know why you agreed to help us?